Yoshinori Hisazumi

A Cogeneration System for an Apartment Building Using Distributed Heat Storage Technology

In order to spread economically viable distributed generation systems for apartment buildings, it is essential to develop an efficient and low-cost heat supply system. We are developing a new cogeneration system (Neighboring CoGeneration system: NCG). The key concept of this system is to install a heat storage unit with a hot water supply and a room heating function at each household and to connect heat storage units by a single-loop hot water pipe. In this study, a simulator was developed to reproduce the dynamic performance of the NCG system that combined cogeneration with solar heat for 50 households, and the environmental load reduction effects of the system were evaluated on the condition that heat supply to all households was ensured. It showed that the gas engine system reduced the primary energy use by 18% in a year. Meanwhile, the SOFC system reduced the primary energy use by 29%.Copyright

Energy Saving Effect of Novel Desiccant Air Conditioner for Zero Emission House

The model of zero emission house [ZEH] made full use of leading-edge energy saving and new energy technology of Japan was exhibited at G8 Hokkaido Touyako Summit held on July 2008. Introduction in Japan is set as the goal of starting popularization of ZEH from 2015, change all newly-built houses to ZEH by 2030 and change all houses including existing house to ZEH by 2050. We have developed new style desiccant air conditioner which can supply dry cool air in summer and warm humidified air in winter by using heated water of solar heat or CGS. In this paper, we publish the energy saving efficiency of the incorporation of this desiccant air conditioner into ZEH and case example of exergy analysis compared with heat pump systems in summer extremely hot day.

Enthalpy and Exergy Analysis of Domestic Desiccant Air Conditioner With Cooling Dehumidification and Heating Humidification Using Process Simulator

To popularize the use of desiccant air conditioners in residences, a system that can supply cooled and dried air in summer as well as heated and humidified air in winter is proposed. An evaporative cooler that affords an increase in cooling capacity and the amount of humidification is used in this system. The results of the enthalpy and exergy analyses, performed using a process simulator, showed that significant exergy losses occurred at the blower, heater, and desiccant rotor. In addition, exergy loss occurred at the direct evaporative cooler in heating humidification. Furthermore, it was found that there exists an optimal water temperature that yields peak exergy efficiency from the desiccant rotor.Copyright

Describing Scenarios of Introducing Highly-efficient Gas Cogeneration Systems to Next-generation Apartment Buildings

Toward realizing a low-carbon society as well as ensuring energy security, there is an urgent need to describe scenarios for future energy systems. A cogeneration system (CGS) is one of key technologies and it is, in particular, promising for apartment buildings because of its high efficiency. This paper describes a scenario of introducing a CGS to apartment buildings in order to analyze the effect of this system using exergy as an evaluation indicator. Results show that dominant exergy losses of a CGS arise in combustor and radiator. Compared with the current energy system, a CGS has a potential of reducing energy consumption by introducing a desiccant air conditioner instead of a conventional air conditioner.

Development of a New Cogeneration System for Local Community

In order for economically viable distributed generation systems for local community to spread, it is essential to develop an efficient and low-cost heat supply system. We propose a new heat supply system presented at the ICOPE-05 Chicago. The key technology for the system is to connect compact heat supply units installed in all the households of the local community, such as a condominium, by a single loop of hot water piping. Phase change material was used for a heat supply unit as heat storage material. However to improve handling ability and to reduce the cost down of the unit, we have developed a new heat supply unit whose heat storage tank is made of plastic. Hot water for space heating is used as heat storage material. Furthermore, we constructed a heat supply system for 7 lived-in households with a 5 kW gas engine and a 42 kW boiler as heat sources.

302 Study on LNG Vaporization and Power System for the Next Generation

1.はじめに LNG(Liquefied Natural Gas)の価格が高騰している.これ に加えて円安が進行しており,原発の停止状態が続く電力 各社の電気料金が値上げされた.LNG はわが国に 1969 年 に導入され,1973 年の石油危機では,エネルギー価格の高 騰で省エネ機運が高まり,電力・ガス大手事業者は,LNG 冷熱発電の開発に積極的に取り組んだ.1977 年にこの冷熱 発電の効率を評価できるエクセルギーの解説書 1) が出版さ れ,当時から 36 年が経過したが,節電の要請からエクセル ギーが再び注目を浴びている.一方,電力会社により建設 された天然ガス直接膨張発電方式の LNG 冷熱発電は,蒸気 火力からガスタービンコンバインドサイクルに置き換えが 進む中,運用停止が進んでいる.またランキンサイクルに よる LNG冷熱発電も建設からまもなく 35年が経過する . そこで本論文では,世界各国の LNG 受入基地に適用でき る次世代 LNG 気化発電システムをエクセルギーデザイン 学により研究し,わが国にこのシステムを適用した場合の 経済効果について検討する.

Exergy Design of Energy Conversion System Using Internet Technology

Exergy evaluation system with cloud computing technology has been developed for anyone to perform exergy analysis on a homepage for various energy conversion systems, such as gas engine, desiccant air conditioner, and fuel cell, etc. In this system, parameter studies on each system can be conducted on the homepage, changing initial conditions. The calculation results are obtained in the form of some tables, graphs, and sankey diagrams so that users can experience a process of minimized exergy loss without any paid software. To provide an example of exergy design, SOFC (Solid Oxide Fuel Cell) cogeneration system for domestic use is described. The results show that exergy loss of the cell stack and some heat exchangers are mainly reduced, increasing power generation efficiency by the fuel utilization ratio.

Development of New Heat Supply Unit Using Latent Heat (Dynamic Characteristics of Heat Storage Unit by a Use of Plate Fin Type Heat Exchanger)

A high efficient co-generation system named “Neighboring Communities Co-generation System” is proposed to a multiple dwelling house. The key technology of this system is to connect home and home with one loop of heat transfer line of one-inch diameter, and to level the heat demand by a heat storage unit in each house. This system requires compact heat storage unit of quick response. In this study, a plate fin type brazing heat exchanger was built and tested as a heat storage unit. Sodium acetate trihydrate with a melting point of about 58°C and paraffin wax with a higher value of 74.8°C were used as the phase change material (PCM). As a result, it was shown that the heat transfer in the heat storage unit was dominated by thermal conductivity in PCM. Paraffin wax showed higher responsibility and higher heat output due to its higher melting point and quite lower super cooling in solidification.